Zimbra and Exchange 2003 with 2 different domains.

Hi everyone,

I'm trying to evaluate ZCS 6 for my company. Fortunately the only deciding factor we have is working calendar / contact sharing between ZCS and Exchange 2003 we have. Unfortunately I wasn't able to get this working.

Our scenario is:
- We have one Exchange 2003 server. This server is set up for company which shares offices with my company. They use their own domain name. The IIS with all Exchange stuff is on the very same server, the AD DC is on other machine though.
- We have our own mail server (which we are going to replace by either ZCS or Exchange). This server is set up for our company and our domain name.
- Both companies have their own AD servers setup for appropriate domain names.
- There are no known network issues between the server and all relevant ports are open.

I installed brand new Ubuntu server (Ubuntu 10.04), then I installed ZCS 6 onto it. I used our AD domain name as initial domain name for ZCS, the DNS records are set for this domain name. So far so good. Right after I checked the official wiki and admin guide to see what I need to do next.
I created sample user in ZCS (with corresponding user in our AD), then I logged onto the server of 2nd company and created new OU for users from ZCS and created contact object for the sample user (just plain contact, no Exchange email address created).
Now, according to all the wiki's / guides / posts I've read, this should be it. So I tried to to make an lookup from webclient for any users from the other company, but none reported availability (and actually no contact was visible from their domain) and it didn't work from the other side either (Outlook did see the test contact, but reported that time schedule is not available).

So, can anyone help with setting up of this and proving that ZCS can cooperate with Exchange for 2 different domains? Is this test possible without actually setting up ZCS completely (I mean with appropriate MX records, with all the SMTP proxies we have, etc etc etc), because I don't have that much man-hours left for this project, so I need to say yay or nay pretty soon...